1. Field of the Invention
This invention generally relates to electric circuit breakers More particularly, the invention deals with an improved low-cost, high-speed circuit breaker mechanism.
2. Description of the Related Art
Circuit breakers are ubiquitous in modern day electric systems, both residential and industrial, and constitute an indispensable component of such systems toward providing protection against over-current conditions. Various circuit breaker mechanisms have evolved and been perfected over time on the basis of application-specific factors such as current capacity, response time, and the type of reset (manual or remote) function desired of the breaker.
With particular reference to residential applications, thermo-magnetic circuit breakers have been conventionally used. Such conventional breakers typically utilize a bi-metal or thermostat metal element deflecting with changes in temperature due to resistance heating caused by flow of electric current through the blades. The thermostat metal element is typically in the form of a blade and operates in conjunction with a latch so that blade deflection releases the latch after a time delay corresponding to a predetermined over-current threshold in order to "break" the current circuit associated therewith.
Latch-based circuit breaker mechanisms of this type generally include an electro-magnet operating upon a lever to release the breaker latch in the presence of a short circuit or very high current condition. A handle or push button mechanism is also provided for opening up the electric contacts to the requisite separation width and sufficiently fast to realize adequate current interruption.
Conventional circuit breaker designs embodying a latch mechanism of the foregoing type are complex in implementation because the latch mechanism and the associated components for realizing the activation and deactivation thereof add significantly to the overall part count for the breaker mechanism. Consequently, such arrangements entail increased material costs as well as assembly costs due to the relatively large number of parts and the increased assembly time.
Further, calibration of such breaker mechanisms is rendered difficult, and repeatability is adversely affected by the high degree of inter-component friction occurring as a result of the plurality of sliding and interacting surfaces associated with the latch mechanism. In addition, the adaptation of latch-based circuit breaker mechanisms for use with remote control arrangements is extremely difficult and complex.
Accordingly, there exists an apparent need for a low-cost circuit breaker mechanism which is based on a simple design and avoids the problems inherently associated with the use of latch mechanisms.